From http://www.holo-impact.de/files/Artikel_Explosive_accuracy_Fh-magazine_2-2008.pdf it is known to transfer delicate structures and even holograms onto metal surfaces by explosions copying a template into the surface. If the template comprises a hologram which is copied into the surface, the copied hologram may be used as a proof of originality in the same way as holograms are used on credit cards and banknotes, for example. However, this known method may as such be duplicated and even copied, i.e. two identical products may be produced which can not be distinguished from each other. Thus, it is impossible to say whether the one or the other of such two identical products has been involved in a particular event, for example.
A method and a device for marking a surface using controlled periodic nanostructures are known from U.S. Pat. No. 8,471,880 B2. According to this known method, an item of information is coded in the form of an image including values representative of the coded information. Then an area of the surface is marked dot by dot with a polarized laser beam to form oriented nanostructures on or in the surface by modulating the laser beam's polarization for each marking dot according to the value of a dot of the image. This known method may also be replicated providing for more than one object comprising the same marked surface.
From http://www.ipm.fraunhofer.de/content/dam/ipm/en/PDFs/Product%20sheet/PK/IMT%20Inline% 20Measurement %20Techniques/Fraunhofer%20IPM_O-PUR_engl.pdf it is known to use surface structures of packaging to reveal product forgeries. This known method takes advantage of the fact that ink used in offset printing on packaging paper spreads individually according to the structure of the packaging paper. The characteristic spread pattern of the printing ink within the matrix structure of the packaging paper provides a characteristic fingerprint for each single packaging. This fingerprint is scanned with high resolution by a camera. The resulting data are stored in a data base. On an actual product, the fingerprint can be read with a hand scanner and checked for authenticity of the product within seconds. Via the internet the scanned fingerprint is compared with the fingerprints stored in the data base. However, a surface pattern or fingerprint which can be scanned and checked for authenticity by a camera even if only by a camera scanning with high resolution can also be copied by optical techniques. Suitable optical printing of photolithographic techniques may be complicated and may not be suitable for counterfeiting or plagiarizing of low or medium cost products. With high valuable products, however, these techniques may be interesting to the counterfeiters. This, for example, applies to high valuable electronics, aircraft components, jewelry and so on.
Zhang, K. et al.: “Surfactant-driven self-organized surface pattern by ion beam erosion”, New Journal of Physics 13 (2011) 013033 report on the self-organized pattern formation on Si surfaces driven by Fe surfactant atoms. Si substrates were irradiated with 5 keV Xe ions at normal incidence under continuous deposition of Fe surfactant atoms. In the Absence of Fe deposition, uniform flat surfaces were obtained. With Fe surfactants, pronounced pattern, such as dots, combinations of dots and ripples and ripples with about 100 nm wavelength, were generated. Pattern formation is explained by ion-induced diffusion and phase separation of the initially flat amorphous FexSi layer and subsequent ion beam erosion with composition-dependent sputter yield.
H. Hofsäss et al.: “The role of phase separation for self-organized surface pattern formation by ion beam erosion and metal atom co-deposition” Appl Phys A (2013) 111:653-664 report the investigation of ripple pattern formation on Si surfaces at room temperature during normal incidence ion beam erosion under simultaneous deposition of different metallic co-deposited surfactant atoms. The co-deposition of small amounts of certain metallic atoms causes the evolution of nanoscale surface patterns on Si. Pronounced ripple pattern formation was found for co-deposited metals (Fe, Mo, Ni, W and Pt), which are prone to the formation of mono and disilicides. In contrast, for Cu and Au co-deposition the surface remains flat. Because of the very different behavior of Cu compared to Fe, Ni and Au compared to W, Pt, phase separation toward amorphous metal silicide phases is seen as a relevant process for the pattern formation in Si in the case of Fe, Mo, Ni, W, and Pt co-deposition.
There is still a need for a method of identifying an original object in fully forgery-proof way.